Yeah but what percentage of users wanted that feature? Microsoft probably knows.
And you can't argue that it's /useless/. It's more information, and, ceteris paribus, more information is better.
Why can't it be both? Being data for Microsoft doesn't preclude it from also being data for you. Being able to just put in a query without having to fire up a browser might be a marginal improvement for a lot of people.
And Microsoft doesn't sell you data. No advertising platform does. They sell access to you, by using your data to classify you in ways you can be targeted. It's a subtle difference, but it changes the implications. If someone is making money off of being able to reliably target you based on your data, that means your data is precious to them. Selling it (or losing it) is tantamount to selling their competitive advantage, such as it may be.
The same graph that will soon feed into the various Copilots and GPT-things to personalize the heck out of your search and document creation which leads to more usage which leads to more data to feed into the graph.
I'm sure some of that "accidentally leaks" into their ad business too (despite their privacy assurances), but again, I doubt they'd ever sell it to 3rd parties (if nothing else, out of fear of litigation... FAANGs usually take PII handling pretty seriously).